The use of communication systems through which to communicate data is an endemic part of modern society. A communication system is formed, at a minimum, of a set of communication stations interconnected by way of a communication channel. Data originated, or otherwise sourced at, a first of the communication stations, referred to as a sending station, is communicated upon the communication channel to be delivered to a second of the communication stations, referred to as a receiving station.
A wide variety of different types of communication systems have been developed, and implemented, as a result of advancement in communication technologies. And, such advancements have also permitted existing communication systems to be improved. For instance, such advancements in communication technologies have permitted the introduction of new types of radio communication systems as well as improvements to existing radio communication systems.
In a radio communication system, the communication channels interconnecting sending and receiving stations are defined, at least in part, upon a radio link defined between the sending and receiving stations. The radio links are formed of portions of the electromagnetic spectrum. Infrastructure costs associated with installation of the network parts of a radio communication system are generally less than corresponding costs associated with installation of a conventional, wireline network. And, a radio communication system can be implemented as a mobile communication system, providing communication mobility.
A cellular communication system is an exemplary type of radio communication system. The network infrastructures of cellular communication systems have been installed throughout large geographical areas of the world, and the usage, i.e., penetration, levels of cellular communication systems is significant.
Historically, cellular communication systems have been used primarily to effectuate conventional, circuit-switched communication services. Such conventional usages of cellular communication systems, include, for instance, circuit-switched voice communications as well as low band width data communication services.
The advancements in communication technologies include, in significant part, advancements in digital processing and communication techniques, resulting in a migration of cellular, and other radio, communication systems to digital cellular, and other radio, communication systems. Second-generation (2G), and subsequent-generation cellular communication systems, are digital communication systems, predicated upon digital communication techniques. So-called 2.5 G communication systems, third-generation (3G), and post-third generation communication systems, e.g., 4G (fourth generation) systems all utilize digital communication techniques. A UMTS/GPRS Universal Mobil Telephone Service/General Packet Radio Service) System, e.g., utilizes digital communication techniques.
Other types of radio communication systems also have benefited from, or have been made possible, as a result of advancements in communication technologies and digital communication techniques. For instance, WLANs (wireless local area networks) have been developed and implemented. WLANs traditionally have, generally, been implemented in the form of private systems. However, increasingly, public wireless communications are extending into WLAN environments. WLANs are advantageously utilized for the reason that high data rate communication services are effectuable therethrough. And, such services are generally effectuable at costs that are relatively less than the corresponding costs of effectuation of such services by way of a cellular communication system.
An IEEE 802.11 operating specification or a variant thereof, sets forth the operating protocols of a communication scheme pursuant to which some WLANs are constructed to be operable.
The bandwidth offered by WLAN is much higher, around 11-54 Mb/s, with much smaller coverage areas around 60 meters within indoors when compared to their 3G counterparts. The WLANs can therefore be thought of as complementary technology to 3G. WLANs are now deployed in hot-spots like airports, hotels, conference halls etc. A 3G mobile user can take advantage of the high bandwidth of WLANs within the hot-spots. The challenge is, how the transition from 3G to WLAN can take place so that the on-going sessions can be maintained without having to re-start the existing sessions that I started by the mobile when it was in the 3G network. That is to say, mobile nodes are sometimes constructed to be operable to permit their operation to communicate by way of a cellular communication system or a WLAN. The separate systems are, however, operable pursuant to separate technologies. And, due to the mobile nature of a mobile node, the mobile node is positionable to communicate, initially, with one of the networks, thereafter to be positionable to communicate with another of the networks.
Data that is to be delivered to the mobile node must be routed to the appropriate one of the network parts. That is, the data must be routed through an appropriate one of the WLAN or the network of the cellular communication system, e.g., the UMTS/GPRS network, to deliver the data to the mobile node in a manner as timely as possible. Having a heterogeneous radio connection allows the data to be delivered to the mobile using either the WLAN or the UMTS/GPRS network so that the mobile could be afforded higher bandwidth and lower delay. Any manner by which better to alert with which of the network parts that the mobile node is resident would facilitate timely delivery of data to the mobile node.
It is in light of this background information related to communications in a heterogeneous communication system that the significant improvements of the present invention have evolved.